Just got the GMC-320+ and went through the manual. There are some issues I can't handle with. I dont need a super accurate device, it's more for curiosity while geocaching/urban exploring.

A) The power-saving method is nice. The motion-detection too.The manual says, if the motion-detection is ON, it wont wake up the device.

A1) It would be nice to have the device at the belt during roaming around and get it out of power-save by alarm/push a button/double tab for a check (I think, thats the idea).

A2) Unfortunately the device wake up by every little movement. And there is no 'ON' in motion detection; just 'OFF', 'On Backlight' and 'On Backlight & DisplayMode'. Whats the difference? Can't get it out...

A3) Is there a way to wake the device up from power-save mode by pressing a button, without changing the display (just wake-up; not use the button as a function button)?

B) The temperature display. Is there any way to gauge that thing? There are never ever 28░C in my office. Two other sources show 15.0░; GMC means 27.8░.

C) How is the gyroscope to use? Is that in a way of factor times a hexadecimal value!? Just see for x, y and z a value like '0xFFE3'.Even when i put it steady on the table it seams to wobbling constantly around...

That's it in the first place.Beside that issues, it's a nice device... will test it by time. Seems to respond on the schist tiles in the floor by +0.08 ÁSv/h... funny.

I just bought a GMC-320 PlusIt started to work fine for a day. When switching on it does its first CPM count, then makes a scratching sound and then the LED light is on fully and the screen just shows "GMC-320 (+v4)" which appears and disappears, and then reappears. Only the Off button works thereafter. I plugged it into my viewer. It ran a bit longer and then scratched and read some crazy ridiculous reading and was dead thereafter coming up with a Comport Error. there was no further reading. I tried this a few times with the same result. Eventually I did a Factory Reset and tried it again. It seems back to normal while plugged into my PC. After unplugging it - it seems to still be working fine. Why did this error occur?? Is it common??

I just bought a GMC-320 PlusIt started to work fine for a day. When switching on it does its first CPM count, then makes a scratching sound and then the LED light is on fully and the screen just shows "GMC-320 (+v4)" which appears and disappears, and then reappears. Only the Off button works thereafter. I plugged it into my viewer. It ran a bit longer and then scratched and read some crazy ridiculous reading and was dead thereafter coming up with a Comport Error. there was no further reading. I tried this a few times with the same result. Eventually I did a Factory Reset and tried it again. It seems back to normal while plugged into my PC. After unplugging it - it seems to still be working fine. Why did this error occur?? Is it common??

The same thing happened to me this morning. I went to plug my USB cable in which is connected to my computer to send data to the radiation map, then pressed the power button. The unit started up and displayed "GMC-320 (+v4)", then would blink white and restart, in an endless reboot loop. I took the battery out and it made no difference. I tried taking the battery out again and then as I was putting the battery holder back into the unit, all of a sudden the screen was asking for the date and time. After that, I did a factory reset, and the unit appears to be working OK, although while in setup in a sub-menu, it would go back to the root menu without me pressing any buttons. Sounds like a flaky unit. The unit is 39 days old as I ordered it on 3-11-17 and I placed it online on ~3-15-17. I hope it doesn't "act up" again. Do I have a warranty?

I had a similar issue: Everytime I touched the USB socket with the cable the unit, let alone pluggin it in - The unit would read a constant pulse. Like a short circuit. I guess this could also damage the unit and result in these issues zebra14 describes. But I dont know what causes this. A while later it work fine.

GMC-300E+ V4.20 with sbt-11a alpha tube

My statements are "stuff-a-hobbyist-says" and not in any way professional.

#1 the unit in reboot loop when power on. That is caused by the corrupted configuration data. The configuration data will be loaded when powering up. But if the data is corrupted, the unit can repair that byte data and reboot again. However, if there are more data corrupted, the unit will have multiple reboots until reset all configuration data. The reason of data corruption is unknown. It could be electric static or power surge for example.

#2 The sub-menu exit itself. This may be related to a software bug, but it is best if you can repeat that problem, so that can fix the problem. If the problem is not repeatable, then it may caused by something unknown.

Distelzombie, the problem may be related to the new tube. Some new tube may have higher reading than normal in first a few minute. but it will have a good stable reading after a few minute or a few power ON/OFF cycles.

@ZLM I was saying that is like a short not just higher readings. That's no understatement. It apparently looks, sounds and does stuff like it is a constant signal. I didn't want to let it do its stuff for more than a 1-2 seconds. That's why I can't tell you the cpm or something. However in these few seconds it rose up to 10k cpm.

GMC-300E+ V4.20 with sbt-11a alpha tube

My statements are "stuff-a-hobbyist-says" and not in any way professional.

#1 the unit in reboot loop when power on. That is caused by the corrupted configuration data. The configuration data will be loaded when powering up. But if the data is corrupted, the unit can repair that byte data and reboot again. However, if there are more data corrupted, the unit will have multiple reboots until reset all configuration data. The reason of data corruption is unknown. It could be electric static or power surge for example.

It's doing it again today - the endless rebooting upon startup. I see the startup logo "GMC-320 (+v4)" and then it reboots. Again and again. I've tried removing the battery and reinstalling it, yet it still goes back to this endless reboot.

About how many times should it reboot before it loads normally?

At what time do I need to send my unit in for repair? Is there a warranty?

Thanks for your help, ZLM!

PS: After about 35 minutes, the unit finally asked for the date and time and appears to be working again. I want to be on record that this malfunction occurred again just in case I need to send the unit in for repair or replacement.

#1 the unit in reboot loop when power on. That is caused by the corrupted configuration data. The configuration data will be loaded when powering up. But if the data is corrupted, the unit can repair that byte data and reboot again. However, if there are more data corrupted, the unit will have multiple reboots until reset all configuration data. The reason of data corruption is unknown. It could be electric static or power surge for example.

It's doing it again today - the endless rebooting upon startup. I see the startup logo "GMC-320 (+v4)" and then it reboots. Again and again. I've tried removing the battery and reinstalling it, yet it still goes back to this endless reboot.

About how many times should it reboot before it loads normally?

At what time do I need to send my unit in for repair? Is there a warranty?

Thanks for your help, ZLM!

PS: After about 35 minutes, the unit finally asked for the date and time and appears to be working again. I want to be on record that this malfunction occurred again just in case I need to send the unit in for repair or replacement.

I had my GMC-320+ V5 for only about a month and today when I turned the unit on it also went into the repeating boot loop. After about 15 minutes it finally went into the "Set date and time" mode and appears to be working normally.

I hope this isn't a recurring issue because for something that cost $150 it shouldn't have this problem in the first place.

All devices come with one year factory warranty. With factory warranty, the service is free. But customer need to cover the shipping cost for both ways.

Your problem seems related to the battery. The LCD backlight uses battery only. So, if the battery dead, no backlight.

Check your battery contacting first, in most of cases the problem only the battery contacting problem. Also check the battery if still OK If the battery contacting and battery itself have no problem, then problem is the main unit.